1. Field of the Invention
The present invention relates to communication equipment, and more particularly to data communication equipment for communicating data such as image data or text data through a line.
2. Description of the Prior Art
Prior art equipment of this type such as a facsimile machine is connected to a telephone line and communicates images through the telephone line. A receiving facsimile machine usually has an auto-receive mode and a manual receive mode so that the telephone line can be used for the image communication and speech communication.
In the auto-receive mode, if a call from the line occurs, the line is automatically switched from the telephone set to the facsimile machine and the image is automatically received in accordance with a predetermined facsimile procedure. In the manual receive mode, an operator responds to the call from the line and the image is received as a result of manipulation of facsimile controls by the operator. When the receiving facsimile machine is in the manual receive mode, the telephone set can be used for speech communication. However, when the receiving facsimile machine is in the auto-receive mode and the sending station wishes to effect speech communication through the telephone set the receiving facsimile machine acts as through an error had occurred because it does not receive the facsimile signal.
The sending facsimile machine may have an auto-transmit mode and a manual transmit mode. In the auto-transmit mode, the facsimile machine automatically calls the line, and when the line is connected, it automatically switches the line from the telephone set to the facsimile machine so that an image can be automatically transmitted in accordance with a predetermined facsimile procedure. However, when the sending facsimile machine is in the auto-transmit mode, speech communication is not possible even if the receiving facsimile machine is set in the manual receive mode to initiate speech communication.
The facsimile machine has an alarm function for generating an alarm sound so that the operator can quickly handle an error, and an auto-dialing function. It may have a sound monitor of the telephone line to allow effective use of those functions. The facsimile machine has a volume controller so that a user can control the sound level. The volume controller is arranged internally or externally of the machine. When it is arranged internally of the machine, the user cannot readily manipulate it and he/she has to call a serviceman whenever he/she wants to adjust the sound level. When it is arranged externally of the machine, cost/performance is relatively poor because it is not frequently used.